1. Field of the Invention
This invention relates to an apparatus and method for drawing liquid samples and dispensing them into a plurality of test tubes, in particular for drawing biological samples, and dispensing them in a single operation into a plurality of test tubes, filled with air or other gas at atmospheric pressure and containing, if necessary, the additives to preserve or prepare the sample for the requested analyses.
It is known that, usually, the analyses requested for each sample are different both in number and type. It is therefore necessary to use a drawing technique which involves the dispensing of the sample into several test tubes, so that in each of them is ensured the quantity of sample of the purity necessary for a particular analysis.
It is also known that the sample must undergo as little handling as possible to prevent the alteration of its components and, if necessary, it must be mixed as soon as possible to the additives necessary to conserve or prepare it for the requested analyses. This is particularly, but not exclusively, important in the case of a sample of blood drawn out of a patient.
2. Description of the Related Art
U.S. Pat. No. 3,848,581 (Cinqualbre and Cinqualbre) describes three different embodiments of an apparatus consisting of a body providing a longitudinal internal duct connected at one end to a drawing needle and at the other end, through secondary crossducts, to many test tubes, embedded into suitlable cavities and left hanging up under said body. In the first and third of said embodiments said test tubes can be filled by shifting them one by one and so opening an outlet to the air contained in them, so that the blood could fill them up in succession to the desired level. In the second embodiment the test tubes are not shifted, the outlet for the air is always open and the test tube to be filled is chosen by shifting a valve member. All the three embodiments are affected by several drawbacks. Lacking any kind of suction means, this apparatus can draw only if a difference of pressure from the drawing element to the atmosphere is present and, in the case of the draws of venous blood, which are normally used, this pressure is very low; this means that the blood flows very slowly and tends to clot, so blocking the flow; to prevent this effect large ducts are required and in particular a large needle, which may be impossible for some patients. The need to manipulate the test tubes or the valve members to open an outlet to the air focuses the operator's attention away from the patient, upon whom it should on the contrary be concentrated, and keeps both of his or her hands employed, while these should be free and used only to look after the patient. It is impossible to programme the precise quantity of sample to be collected into each test tube, being this left to the skill of the operator. The whole operation is unsafe, because the test tubes are not locked to their recesses and, if their fitting is tight, they are difficult to shift and make it difficult to use the apparatus and, if said fitting is loose, the test tubes are likely to come out and spill their contents, both during the draw, because of some error of the operator or some movement of the patient, and especially during their recovery; even worse, during this last operation, the operator must handle the body of the apparatus which is certainly polluted by the sample while one or more of the filled test tubes have already been taken out, so exposing him or her to a high risk of contamination. The apparatus is completely contaminated by the sample and, being too expensive to be disposable, it must be disassembled and sterilized after each single draw.
U.S. Pat. No. 4,649,967 (Gruenstein Eric I. et Al) describes an apparatus designed to transfer simultaneously samples from one or more containers into a plurality of uptake containers singularly airtightly connected to a common vacuum source through a three positions valve; this configuration makes it possible to disconnect the vacuum source and operate on the containers and the ducts connecting them when the valve is kept in a first position, to suck the samples when the valve is kept in a second position and to stop the flow while mantaining the vacuum when the valve is kept in the third position. This apparatus cannot be conceptually used to collect different preprogrammed amounts of sample into the different uptake containers and therefore it is unsuitable for drawing biological samples, expecially blood. Moreover it has some drawbacks: the suction speed cannot be controlled and the force of said suction may produce some foam, with consequent breaking of the cellular membranes, so damaging the sample during the draw; the depression left inside the test tubes after their filling can be a cause of an unwanted ejection of material at the opening of the valve, so making it probable the contamination of the common bore and in consequence the need to clean of the whole apparatus after each draw.
FR-A-1.247.657 (United Kingdom Atomic Energy Authority) relates to an apparatus designed for collecting a sample of a liquid flow representative of its content during a long period, normally many hours; this is obtained by sucking very slowly a small portion of said fluid out of the flow and into a long pipe connected at the other end to a very slowly varying vacuum source through a bottle, into whose cap an input and an output tubes are airtightly inserted, and then taking said pipe out of the fluid stream and emptying it into said bottle slightly increasing the vacuum. After the change of the bottle the whole process can be started again. Many bottles can be filled with samples collected from many liquid flows using the same vacuum source. This apparatus is designed for collecting samples over a long period in a fixed plant: it needs a plurality of drawing elements and a plurality of valves, one of each for each bottle or test tube, a big vacuum apparatus and a big container connected to a slow flowing source of water or other auxiliary liquid and therefore it is very slow at drawing, cumbersome and unsuitable for mobile applications, such as collecting samples for the normal biological analyses.
EP-A-0107579 (Le Material Biomedical) describes a cylindrical container providing a cap which can slide fluid-tightly into it and is connected to a stem; driving manually said stem, such a container can be filled as a syringe, then said stem is broken, transforming it into something similar to a test tube. By connecting to the drawing needle a hose which is split at the other end into many branches, many test tubes, also of different dimensions, can be filled one after the other during the same draw. This system solves the problem of filling many test tubes in a single draw, but it is awkward to handle; it takes a lot of time to complete a draw and needs the whole attention and the use of both hands of the operator to be carried out; furthermore, it is potentially dangerous for the operator who disconnects the test tubes, which are open, from the branches of said hose, both of them being polluted by the sample which can easily spill over.
EP-A-0154002 (Ferring Biotechnik GmbH) describes a programmable apparatus designed for carrying out researches into the biological rhytm, apt to be carried around by a person and to draw samples of blood at stated time intervals, leaving said person free to go around in a normal way. It is a complex, and therefore expensive, apparatus, designed for a very peculiar use, in which the suction means (a pump) act directly on the means connecting the drawing means (needle) and the containers of the samples and which uses, to store them serially in a hose and dispense them to different containers, a multiple-way valve which is subject to contamination and therefore must be disassembled and sterilized every time the set of drawing operations performed on a person is over. Said apparatus is therefore unsuitable for the normal drawing operations, which need high operating speed, low running costs and well defined procedures of use, because it has a low utilization factor, a uselessly high cost, and it compels the operator to handle frequently potentially contaminated components and therefore to undergo a high risk.
Actually, the necessity to carry out draws, especially of blood, in a swift way and without polluting the sucking element, is increasingly becoming such a pressing necessity that it has urged the development of many devices based on the principle of the indirect suction.
It is known that for achieving this goal are widely used test tubes providing an inside programmed depression, which, when inserted on a secondary needle connected through a duct to the drawing needle, can collect into them by suction a desired quantity of blood. All these devices make it necessary either to pierce the vein as many times as there are test tubes to be filled or to leave the needle inserted into the vein for the time being, while the operator inserts successively the secondary needle into the required test tubes, so compelling him or her to use both hands, which should on the contrary be free for taking care of the patient. Moreover said test tubes have several drawbacks: the depression, generated in them when manufactured, decays with time; the suction speed cannot be controlled and the force of said suction may produce some foam, with consequent breaking of the cellular membranes, so damaging the sample during the draw; their cost is high, much higher than the normal test tubes; a residual depression, which can be the cause of an unwanted ejection of material at their opening with potential contamination risk for the operator, is left inside the test tubes after their filling.
Moreover, devices were developed that make it possible to transform the container used to draw the blood into a test tube.
For instance, EP-A-0107578 (Le Material Biomedical) discloses a particular cylindrical container providing a cap which can slide fluid-tightly into it and is inserted in between a drawing needle and a syringe through two couplings also fluidtight; by moving manually the piston of the syringe, a depression is generated upstream of said cap which therefore will slide from the needle end side to the syringe end side, while sucking, in consequence, the blood into said cylindrical container on the other side of the cap, so transforming it into something similar to a test tube. But such a device can only be used to draw a fixed quantity of sample, because the movable element must run through the whole stroke to reach the position in which it surely seals the outlet from which the air was sucked out. Therefore, even if it were modified so as to fill in one stroke several test tubes, this solution would be complex to assemble and disassemble and therefore dangerous to use, and it couldn't anyway provide, as necessary, a collection of predetermined different quantities of sample into each of a plurality of test tubes according to the needs. Also, an immediate mixing with any additives requested could not be provided.
U.S. Pat. No. 4,216,782 (Sarstedt) discloses a similar cylinder providing an inside cap, which slides fluid-tightly, where the sample is collected and can afterwards be used as a test tube, but into which, before the draw, a depression is generated, so performing the draw in a way similar to that previously seen for test tubes with a programmed depression inside. This device has the same drawbacks already seen and one more, that is the need to pierce the vein as many times as there are test tubes to be filled.
EP-A-0150127 (Bilbate Limited) discloses a special syringe which makes it possible to carry out a draw by pushing a piston instead of pulling it out, and therefore using only one hand. According to said patent the blood is collected directly into a test tube sealed by a membrane, into which two needles are inserted, a sucking one connected to said syringe and the other connected to the drawing needle, inserted into a removable component which houses the drawing needle too. Such a device makes it necessary either to carry out as many draws, and therefore to pierce the vein as many times, as there are test tubes to be filled or to dispense later the sample into the requested test tubes, and it is extremely critical to use, because no support is provided for the test tube which can easily slide off the needles during the draw, and in addition is placed necessarily in contact with the patient's arm with no support, in a clearly precarious position. Moreover, after the draw, it is necessary first of all to extract the test tube, leaving to the operator the task of screwing out of the syringe the removable component which has two bare needles exposed, polluted by the sample. This operation is extremely dangerous.
U.S. Pat. No. 5,110,557 (Brown Bradley V. et Al) describes a hand held blood sample collection apparatus providing a special test tube with a special cap, into which the blood is sucked by means of a battery powered vacuum pump; being the core of the invention the actual configuration of said cap and of its connections, it can structurally be used for one test tube only, since said cap is designed for one single test tube. Such an apparatus may be seen as a improved version of a normal syringe, but it sums up some of the drawbacks of the use of a single syringe--the quantity of sample collected is not exactly programmable, the blood must be later manually dispensed to all the necessary test tubes--to some of the drawbacks of the test tubes with an inside programmed depression--the velocity of the inflow cannot be controlled, with all the inherent consequences.
Among all these devices the only ones of widespread use are, in spite of their mentioned drawbacks, those sucking the sample into a test tube within which a depression is produced either at their manufacturing or immediately before the draw, while is still widespread the operation in two phases, consisting of the collection of the sample into a single syringe and its successive distribution into many test tubes, a dangerous operation because it exposes the operator to the risk of infection and the sample to a waiting time and some handlings which might spoil it.